researchers in Denmark has now identified genetic factors associated with the emergence of permanent teeth. They analyzed DNA from nearly 9,000 individuals in Denmark and the United States, and found four SNPs that influenced the timing and number of visible teeth at various ages.For at least three of these SNPs found in this study, the version associated with fewer teeth is relatively common in the population. And although the individual effects of the variants are small – correlated with about half to one tooth fewer, on average – they did seem to add up. In this study, someone with two copies of the “delayed tooth eruption” version at all four SNPs had about six fewer teeth (16 teeth) at 10-12 years of age compared to someone with no copies of the delayed versions (22 teeth). Interestingly, a study published a few years ago showed that two of these SNPs might also play a role in the eruption of baby teeth. Some genetic factors contribute to multiple growth-related traits, so the authors tested if the tooth development SNPs were also linked to traits such as age at menarche (first period in young women) and adult height. In general, the genetic factors underlying these traits did not overlap. There was, however, weak evidence suggesting that several of the SNPs associated with permanent tooth development also influence adult height and breast cancer. More research is needed to determine the exact biological mechanisms linking these different traits.This study represents the first GWAS to look for genetic factors involved in permanent tooth eruption. Studies like this one are interesting because they reveal that there is clearly natural variation across the population–some individuals have more teeth while others have less. These findings also highlight the complex interplay between genetic factors involved in human growth and development.SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.